Phonograph needle



y l941- H. 1.. IMELMANN 2,249,713

PHONOGRAPH NEEDLE Filed Nov. 4, 1940 Patented July 15, 1941 um'rao V'STATES PATENT OFFICE PHONOGBAPH NEEDLE Henry Louis Imelmann,

Permo Products Corporation,

corporation of Illinois Application November 4, 1940, Serial No. 364,210

Claims.

- scription and accompanying drawing, in which:

Fig. 1 represents a sideelevation of a needle embodying my invention;

Fig. 2 represents a longitudinal cross section of such a needle; and

Fig. 3 represents a top plan view thereof.

Fig. 4 represents a longitudinal cross section of a modified form of aneedle embodying the invention.

After considerable experience in the manufacture of phonograph needles,and after extensive tests, I have found that the frequency range of aneedle may be precisely controlled by carefully gauging both thediameter and the length thereof.

Tests have shown that by decreasing the diameter of the lower tipportion of a needle it does not respond to that frequency range coveredby the usual "scratch" of the record resulting from mere mechanicalfriction between the point of the needle and the walls and bottom of therecord groove. The latter friction "scratch is to be distinguished fromdesired tones resulting from the predetermined vibration of the needlepoint in the undulations of the record groove.

In thinning out the lower end of a needle it has been found that most ofthe necessary rigidity and strength is lost, with the result thatwhenthe pick-up head is accidentally dropped against the record, thestrain placed upon the needle point and body is too great and it is bentbeyond the fatgue point of the metal and thus rendered useless, since,under such circumstances the metal Chicago, Ill., assignor to Chicago,111., a

bushing element 4 which is swedged within the sheath.

It is contemplated that the distance between the adjacent surfaces la.and la of the needle I, and the protective extension 8, be great enoughto permit free vibration of the needle portion during playing and lessthan or equal to the distance through which the needle body can be bent(see dottedlines of Fig. 2) without reaching its fatigue point, beyondwhich point it will not spring back to its original alignment. From thelatter fact it will be seen that this space between the surfaces will begreater or smaller, depending 1 upon the diameter and length of theneedle body.

has been distorted to such a degree that it will I not return to itsoriginal alignment.

The embodiment shown in the drawing comprises three principal sections;a needle or playing portion l, having-a point 1-1), a shank or holdingportion 2, and a relatively rigid sheath or protective extension 3.

The needle i may be secured in the sheath 3 in any suitable manner, as,for instance, by a As the needle diameter and length are decreased orincreased the distance between the surfaces must be decreased orincreased respectively.

It is also contemplated that the extension 3 may comprise a prong-likeextension 5,.as shown in Fig. 4, the extension 5 taking a position overthe needle'body to be abutted by the needle when the pick-up head isdropped on the record either accidentally or customarily as in some ofthe automatic record changing systems. 'In this construction the playingportion l is seciuredz directly in the body of the holding port on Inorder that the relative sizes of the parts shown be understood by thoseskilled in the art, it may be mentioned that the diameter of the portion2 of the embodiments shown here substantially represents the diameter ofthat portion of needles now generally used which is engaged in thepick-up head of a phonograph tone arm. From the foregoing it will beseen that a structure has been provided wherein the needle may bedistorted only to a limited degree, the limit established being suchthat the needle cannot be bent beyond the fatigue point of the metalfrom which it is made. Under such circumstances when the needle body isbent the maximum amount established, it will always spring back to itsoriginal form. a

It will be seen that I have provided a phonograph needle which, whilehaving a reduced diameter, is protected against bending and is at alltimes retained in alignment within its range of fatigue through bending.

Having thus described my invention, what I claim as new and desire tosecure by Letters Patent of the United States is:

1. In a phonograph stylus, a playing portion having a point at one end,a shank portion, said shank having a substantially concentric borelongitudinal of the shank thereof, said playing portion extendingsubstantially concentrically into said bore and being secured thereinwith its point protruding therebeyond in spaced relation to the insidewall of said shanl: at the lower end. I

2. In a phonograph stylus, a playing portion having a point at one end,a shank portion, said shank having a substantially concentric borelongitudinal oi the body thereof, said playing portion extendingsubstantially concentrically into said bore along its principal axis andbeing secured therein with its point protruding therebeyond, said borebeing of a greater diameter than that oi end.

3. In a phonograph stylus, a playing portion having a point, aholdingportion for engagement with a phonograph reproducensaid playingportion having its end remote from the point and secured to said holdingportion and in spaced relation with said playing portion, a protectiveelement on said holding portion, said protective element having one endintegral with said holding portion and extending adjacent to and spacedfrom the playing portion toward the point thereof.

the playing portion at its lower 4. In a phonograph stylus, a playingportion having a playins punt, means at the end' of said playing.portion remote from its point for engagement with a phonographreproducer, a relatively rigid protecting element on said stylus, saidlast named, element having one end adjacent to and spaced from saidplaying p rtiomsaid space sumciently large to permit normal vibratinn ofthe stylus without contacting said protecting element while playing andsumciently small to prohibit the bending of the stylus beyond theelastic limit of the material from which it is made.

5. In a phonograph stylus, a playing portion having a playing point, oneend of said stylus being adapted to engagement in a phonographreproducer, a relatively rigid protecting element for said playingportion, said last named element having one part thereof adjacent to andin spaced relation with said playing portion in the region of saidplaying point, said space being sufficiently large to permit normalvibration of the stylus during playing and suiliciently small toprohibit the bending of the stylus beyond the elastic limit of thematerial from which it is made.

HENRY LOUIS IMEIMANN.

